An ebonite beam B is rocked up and down rapidly by a train of mechanism, and moves the cranks FIG.
The operation is as follows: the paper ribbon or perforated slip is moved forward by its centre row of holes at the proper speed above the upper ends of the rods S, M; should there be no holes in the ribbon then the cranks A, A' will remain stationary, although the beam B continues to rock, since the rods S, M are pressing against the ribbon and cannot rise.
All cylinders drive on one crank-axle with three cranks at 120°.
The low-pressure cylinders drive on the leading crank-axle with cranks at right angles, the highpressure cylinders driving on the trailing wheels.
In this engine the two piston-rods of one side are not coupled to a common cross-head, but drive on separate cranks at an angle of 180°, the pair of 180° cranks on each side being placed at right angles.
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